The invention relates generally to ultra-wideband sensors, and more particularly to ultra-wideband range-gated proximity sensors.
U.S. Pat. No. 5,345,471 by McEwan describes an ultra-wideband (UWB) receiver which has both differential and single-ended configurations. The UWB receiver is range-gated and has a variety of micropower impulse radar applications, including motion sensing (U.S. Pat. No. 5,361,070), hidden object locators (U.S. Pat. Nos. 5,457,394 and 5,512,834), and medical monitoring (U.S. Pat. No. 5,573,012). U.S. Pat. No. 5,609,059 describes a guided wire micropower impulse radar system for material level sensing. U.S. patent application Ser. No. 08/379,044 describes an RF switch for material level sensing. U.S. Pat. No. 5,521,600 desribes a range gated field disturbance sensor and U.S. Pat. No. 5,581,256 describes a range gated strip proximity sensor.
It is desirable to have a simple, low cost UWB sensor which can detect changes in impedance to replace conventional impedance sensors for use in a variety of applications. Magnetic proximity sensors are useless where nonferrous materials are to be sensed. Capacitive sensors are affected by interferences, e.g., moisture. Conventional microwave CW impedance bridges can be affected by spurious Doppler modes from large distant objects.